Voltage multiplier



Ap 1951 A. c. VAN DORSTEN 2,549,995

VOLTAGE MULTIPLIER 1 Filed Aug. 3, 194a ADRIANUS CORNELIS VAN DORSTEN INVENTOR Patented Apr. 24, 1951 VOLTAGE MULTIPLIER Adrianus Cornelis van Dorsten, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application August 3, 1948, Serial No. 42,282 In the Netherlands August 27, 1927 4 Claims. 1

This invention relates to an electric voltage multiplier and has for its object to assemble in a suitable manner the elements constituted by condensers and rectifiers and connected in cascade.

The most commonly used construction of voltage multipliers with cascade connection of condensers and rectifiers has hitherto been that in which the condensers constitute two parallel columns. In this system the condensers are electrically connected in cascade by means of metallic intermediate pieces. The rectifiers are pro vided in an inclined position between the columns and are secured, at their extremities, to the intermediate pieces so as to be also electrically connected to the condensers.

In a further arrangement which is also known the rectifiers are united to form a separate column which is placed in parallel with the two other columns and in which the rectifiers are electrically connected in cascade, the cascade connection being completed by connections between the columns. In'this method of arrangement the height of the whole device is determined by the column of the rectifiers, since it comprises a number of elements equal to that of the two other columns together and the rectifiers seldom have a, smaller, most cases a greater length than the condensers.

The voltage multiplier according to the invention is. likewise constituted by three columns, but it differs from the known constructions in that the elements of each column are constituted by alternately a condenser and a rectifier. The rectifiers are connected in cascade by providing connections between the columns, which lead at each instance from the upper extremity of a rectifier in one column to the lower extremity of a rectifier in the subsequent column.

. The invention. will now be explained more fully by reference to the accompanyin drawing showing diagrammatically, by way of example, two forms of voltage multipliers with cascade connection, viz.

Fig. 1 shows a device of the known two-column system and Fig. 2 a device with the arrangement according to the invention.

Fig. 3 is a cross-sectional view of this arrangement;

The device shown in Fig. 1 comprises two columns I and 2. Column I comprises four condensers 3', 4, 5' and 6, marked with X in the drawing. Column Z also comprises four condensers I, 8; 9 and II marked with Y in the drawing.

Ali

The condensers are electrically connected to one another and to the rectifiers R by means of metal intermediate pieces I I. The rectifiers hang main inclined position between the columns and are secured, at their extremities, to the intermediate pieces.

' Column I rests on an insulator I2 and column 2 on an earthed metal foot I3. A metal connecting body I4 provided on the lower extremity of condenser 3, has secured to it a supply conductor I5 for connection with a source of alternating voltage to which the series combination constitut'ed by condenser 3 and rectifier I6 is connected. When the device is put into use, condenser 3 is charged to the maximum value V of the alternating voltage, the other condensers being charged to approximately twice the voltage V. For this reason condenser 3 need be only about half as high as the other condensers.

An insulator I! is provided on the uppermost intermediate piece of column I. On the said insulator and on a metal closing member I8, by which condenser I0 is connected torectifier. I9, rests a metal pole body 20, which is electrically connected to the closing member I8 and which exhibits a rounded surface in order to avoid spray phenomena. A consumer circuit may be connected between the pole body 20 and earth. The condensers Y are connected in series with respect to the supply current, all the rectifiers being connected in cascade via the intermediate pieces II. This does not imply that they are connected in series, since during the half waves of the alternating current in which current flows through those rectifiers via which the condensers X are charged, the rectifiers through which thecon-v densers Y are charged exhibit no current, and conversely.

Instead of being secured to the condenser columns, the rectifiers may be united, as is well; known, to form a separate/isolated column, so that there are in this case three columns, but the height of the device is thus considerably increased. With the arrangement according to the invention as shown in Fig. 2, the device, although also constituted by three columns, becomes lower instead of higher than the device shown in Figure 1.

As shown in Figure 3. the three columns 21, 22 and 23 are placed in the corners of a triangle. Each of the three columns comprises alternately a condenser (X or Y) and a rectifier (R) and therebetween a metal junction body by which the successive elements are interconnected electrically and mechanically. The marks X and Y on the condensers have the same meaning as those in Fig. 1. Column 2| rests on an insulator 24 and columns 22 and 23 on earthed metal feet 25 and 26 respectively. Column 23 comprises one element less than the two other columns, but it exhibits an extension in form of an insulator 29.

The three columns are interconnected by means of conductors which are secured to the metal junction bodies. Thus, the conductor 3! connecting the junction bodies 2! and 22, leads from the upper extremity of rectifier 33 in column 22 to the lower extremity of rectifier 3G in column 2|. The upper extremity of this rectifier is connected, by means of conductor 35, to the lower extremity of rectifier 3G in column 23. A conductor 31 leads from the upper extremity of rectifier 36 back to column 2., that is to say to the lower extremity of rectifier 38. The other rectifiers are connected to one another in a similar manner.

The upper extremities of the last rectifier provided in column '22, and of condenser in column 21 are interconnected by means of a pole body 4|, which rests on the three columns, the lower extremities of the first rectifier in column 22 and of condenser 42 in column 23 being connected to earth.

The source of supply, a transformer 43, is on the one hand connected through a conductor 4 to the metal junction body 45 with which the lower extremity of condenser 45 makes contact and is, on the other hand, connected to earth. A consumer circuit may be connected between the pole body 41 and earth.

The first group of the system is thus constituted by condenser 46 and rectifier Condenser 46 is charged to the maximum voltage V of the transformer, the other condensers assuming a voltage of approximately 2V. As a result of the mutual connections of the columns the condensers Y are connected in series with respect to the supply current.

The three-column system shown in Figure 2 comprises four elements more than the twocolumn system in Fig. 1 and hence provides a voltage which is about 25% higher. The elements are shown of equal size in the two figures. In the device shown in Figure 2, each of the columns 2| and 22 comprises seven elements in all, that is even three more than each of the columns shown in Fig. 1. Nevertheless it appears from the figures that the method of assembling according to the invention results in an appreciable smaller height of the device. This is attributable to the fact that the metal junction members may be lower than the closing and connecting pieces shown in Fig. 1. In the construction shown in Figure 1, the intermediate pieces H are required to be of a height such as to permit the securing of two rectifiers, whereas in that shown in Figure 3 the junction bodies need be only of sufiicient height to enable the cross-connections to be secured thereto,

By providing the rectifiers beside instead of between the columns, it would be possible to modify the arrangement shown in Figure l in such manner that the intermediate pieces and closing pieces may be chosen of smaller height, but nevertheless a construction ensues which is inferior, in mechanical respect, to that accord ing to the invention in which three points of support instead of two are present and the columns are loaded by weights not higher than those of the connecting conductors 30, 35, 31, etc.

From the structural viewpoint, each of the elements of the voltage multiplier is constituted by a rigid envelope of insulating material which ensures sufiicient rigidity of the columns and in which the electric member which is mechanically unloaded is safely enclosed.

In devices designed as shown in Figure 1, the rectifiers used in most cases discharge tubes comprising a thermionic cathode. It is alternatively possible to utilise a battery of blocking-layer cells, for example of selenium cells, which do not exhibit the disadvantage that means for heating thermionic cathodes are required. This disadvantage is not of much importance in the two-column system since the closing and intermediate pieces always aiford suilicient space to receive transformers (supplied by high-frequency alternating current) or accumulators for providing the heating current for the thermionic cathodes.

Now that an arrangement according to the invention permits of substituting the high intermediate pieces shown in Fig. 1 by low junction bodies, the use of batteries of blocking-layer cells as rectifying elements becomes more attractive, since this use permits 01' taking full advantage of such an arrangement owing to the fact that in choosing the height of the junction bodies there is no need to reserve space to receive means for generating or transforming heating current.

Furthermore, the voltage multiplier according to the invention, owing to its decreased height, is preferred more than that employed in one of the known forms of arrangement of the elements, to be enclosed, if desired jointly with the transformer, in a metal vessel 49. In order to fix the maximum potential difference between the wall of this vessel and the voltage multiplier, the wall is connected to a point of the electric system, for which purpose, as a matter of course, the lower extremity of rectifier 33 enters first into consideration. The vessel is then also connected to earth. Instead of the necessary dimensions of the assembly constituted by columns and envelope being increased by the presence of the vessel, they may on the contrary be considerably decreased, provided that the vessel is filled with a liquid or gaseous medium exhibiting better insulating properties than air at atmospheric pressure. For this purpose use may be made of nitrogen at increased pressure, for example of 10 atmospheres. As is well-known, numerous chemical compounds also exhibit well insulating properties, for example sulphurexafiuoride, which exhibits, at a pressure of 3 atms., a resistivity to puncture such that a voltage multipler according to the invention built up with a height of cms. and enclosed in this gas is suitable for use at a direct voltage of 1000 kilovolts.

It causes difficulty to lead the current at the high voltage provided by the device through the wall of the vessel. This difliculty is suppressed if the consumer is combined with the voltage multiplier to form on unit and is also placed in the vessel. If the consumer (as a rule an electric discharge tube, such as an X-ray tube or an ion-ray tube) is arranged in parallel with the columns, this does not necessarily involve an increased length of the vessel, since the spacing of the poles of the consumer may be equal to that of the voltage multiplier. In order to avoid also an increase of one of the transverse dimensions, the consumer 41 (Fig. 3) is adapted to be arranged at the centre between the columns of the voltage multiplier and hence at the star point of the triangle at the corners of which the columns are placed, this being an ararngement which otherwise is also advantageous if the protective envelope is omitted.

Discharge tubes for use at very high voltage in most cases comprise intermediate electrodes providing even distribution of the voltage over the tube. If the consumer 41 is such a tube, the intermediate electrodes and the metal junction bodies may be connected by conductors 48.

The minimum length of the elements and supporting insulators is determined by the highest electric load which is permissible along the insulating surface. This enables condenser 46 to be made shorter than the other condensers. From the foregoing it follows that there is no reason to give the envelopes of the rectifying elements a length different from that of the condensers, since both have to resist the same electric load. If, however, for some reason or other it should not be possible to make the one kind of elements as short as the other, this does not result in contradistinction to the arrangement comprising two columns of exclusively condensers and one of exclusively rectifiers, in any appreciable difierences in length of the columns, since the number of rectifiers and condensers in each column differs by one at the most.

It may be observed that it is not necessary to position the columns vertically and more particularly such is not the case with arrangement in a greatly insulating medium and hence greatly decreased length of the columns. The columns, provided they are of sufficiently rigid construction or rigidly secured by insulating rods or ropes, may be positioned horizontally. Consequently, whenever in this discription reference is made to lower extremity and upper extremity, this does not imply that the first point is always closer to the surface of the earth than the second and lies vertically underneath, but this only means to indicate opposite extremities.

Furthermore it is mentioned that in this discription the term voltage multiplier has to be understood to mean not only a device fed by alternating voltage and converting this voltage into higher direct voltage, but has to be considered to include also a device with cascade connection which, supplied with direct voltage,

the subsequent column, complete the cascadeconverts this voltage into lower alternating voltage. The use of blocking-layer cells for the time being only enters into consideration for voltage multipliers for alternating voltage supply, since for the second catagory, as is well known, the presence of a control electrode in the rectifying elements is required.

What I claim is:

1. An electric voltage multiplier constituted by elements which are assembled to form three parallel columns and which are electrically connected therein in cascade, said elements being constituted by condensers and rectifiers which are connected in cascade by mutual connections of the columns, characterized in that the elements of each column are constituted by alternately a condenser and a rectifier and that the connections between the columns which at each instance lead from the upper extremity of a rectifier in one column to the upper extremity of a rectifier in connection of all the rectifiers.

2. A voltage multiplier for alternating-voltage supply as claimed in claim 1, characterized in that the rectifying elements are constituted by a battery of blocking-layer cells, for example selenium cells.

3. A voltage multiplier as claimed in claim 1, characterized in that it is enclosed in a metallic vessel which is connected to a point of the electric system and which may be filled with a liquid or gaseous medium exhibiting better insulating properties than air of atmospheric pressure.

4. An assembly constituted by a voltage multiplier as set forth in claim 1, characterized in that the columns are placed at the corners of a triangle and terminals for connecting the multiplier to a load positioned in parallel with the columns at the star-point of the triangle.

ADRIANU S CORNELIS VAN DORSTEN.

REFERENCES CITED UNITED STATES PATENTS Name Date Bouwers June 3, 1941 Number 

